PROJECT SUMMARY/ABSTRACT Human cytomegalovirus (HCMV) infection is the leading infectious cause of congenital disorders in newborns. Congenital HCMV infection causes permanent neurological and neurocognitive disabilities and results in significant health problems worldwide. Our preliminary findings reveal that Notch pathway is affected by HCMV infection and probably via interaction with CMV-encoded protein, IE1. Therefore, we propose to explore the molecular pathogenic mechanism via Notch pathway underlying abnormal brain development caused by congenital CMV infection. This proposed approach is fundamentally different from previous studies because we apply our unique technologies to explore the mechanisms that CMV employs to interfere with the brain development of embryos. We will apply the in vitro HCMV infection system, in utero electroporation system for mouse CMV (MCMV) gene delivery, conditional transgenic mouse model, and intraplacental MCMV infection system. Our long-term goal is to reveal the mechanisms underlying CMV-induced congenital neurodevelopmental disorders and develop potential anti-CMV therapeutics. We hypothesize that the coordinative interaction between CMV and Notch signaling is the key to causing developmental defects of infected neural progenitor cells (NPCs) in embryos, resulting in permanent neurological and intellectual disabilities. The hypothesis is supported by our preliminary data and publications from in vitro and in vivo experiments that HCMV infection affects Notch signaling, that Notch signaling is involved in CMV-caused defects of NPC proliferation, that IE1 is essential and sufficient to inhibit NPC proliferation, and that IE1 interacts with proteins of Notch signaling pathway. We will test our hypothesis via the following Specific Aims: Aim 1. To examine molecular mechanisms for how HCMV IE1 causes defects of human NSC/NPC proliferation and differentiation in cell culture; and Aim 2. To examine how the CMV IE1 causes different stages of neurogenic defect using an IE1-inducible transgenic mouse model and a clinically- relevant intraplacental MCMV infection mouse model. We believe that the present proposal is innovative in several points: First, this is one of the first studies that uses an inducible transgenic mouse model introducing a specific CMV protein, IE1, to address molecular mechanisms underlying congenital CMV infection. Second, we study the congenital CMV infection pathology from molecular levels to behavior levels. Lastly, investigators with different professional backgrounds (virology and neuroscience) are working together to address an important question with high medical impact. Positive impacts will include qualitative advances in understanding molecular virology and CMV pathobiology in particular, and that understanding the mechanisms CMV uses to cause neural defects may thus drive development of new, selective anti-CMV therapeutic strategies.